Many developers have tried and failed to build over the Mass Pike. (It's the Gordian Knot of development.) But the Simon Property Group is determined to deliver its first air rights project—the $500M addition to Copley Place—and just hired the interiors architect to complete the design.

For its biggest current development project, the nation’s largest public real estate company retained ODA Architecture of New York, planning to complete construction documents this year and start building next spring, Simon’s VP of design Gaylon Melton tells us. To meet the structural challenge of finding solid ground, the team will use technology refined for the Big Dig to stage equipment on a deck over the highway and from there, work underground. They’ll erect a concrete slurry wall to protect the transportation infrastructure—trains and the Pike—and build a steel support resembling the Eiffel Tower for lateral stability, he says. Construction of the foundation and support structure will take a year.

The interior of the 625-foot residential tower—109 condos and 433 apartments—that will accompany 115K SF of new retail is still undefined. But ODA founder Eran Chen (above center, white shirt) intends for it to be contemporary, international, and elegant to echo Boston’s strong economy, growing global cache, and reflect the unique site that straddles the historic Back Bay and South End. To create a new level of luxury living, the vast interior space will also be intimate and personal through the choice of materials and space configuration. The amenities will provide a “world of activities”: perhaps a spa, wine storage, private entertaining, and meeting rooms.

To give each residence panoramic views of the city and Charles River, the building has no corners. Their simplicity will reflect today’s lifestyle, Eran says. With an eye on the future, the building design will incorporate Boston’s new energy code with more efficient mechanical systems, glazing material, light fixtures and roof, Gaylon adds. The amenities will be concentrated on the 5th and 6th floors so residents don’t have to stay home to enjoy great views.

Simon purchased Copley Place in ’02, and started planning for the upgrade in ’07. Delayed by the recession, in 2011 it sought and won city approval for the retail and an all-condo high-rise (core and shell designed by Elkus Manfredi). As the apartment rental market strengthened, the retail giant altered its plan for the complex, which was first built in ’84. Prices haven’t been set yet, but Simon is shooting for a landmark building with top of the market pricing, Gaylon says.